You can keep the machine running overnight. Usually those machines should have a sensor that turns the machine off if the temperature gets too high, so it doesn't burn down your home/facility. But I'd double check if your machine has a sensor. You can also switch it off at night, but this means your chocolate will set if the temperature of your room is too low. In that case you could warm up your chocolate in the drum in your oven. But you have to be careful with the temperatures. I wouldn't use a setting higher than 50C/120F on your oven otherwise you could melt the plastic parts of your drum.
